Thermally enhanced semiconductor package with thermal additive and process for making the same

ABSTRACT

The present disclosure relates to a thermally enhanced semiconductor package, which includes a module substrate, a thinned flip chip die over the substrate, a first mold compound component, and a thermally enhanced mold compound component. The first mold compound component resides over the module substrate, surrounds the thinned flip chip die, and extends above an upper surface of the thinned flip chip die to form a cavity over the upper surface of the thinned flip chip die. The thermally enhanced mold compound component includes a lower portion filling a lower region of the cavity and residing over the upper surface of the thinned flip chip die, and an upper portion filling an upper region of the cavity and residing over the lower portion. A first average thermal conductivity of the lower portion is at least 1.2 times greater than a second average thermal conductivity of the upper portion.

RELATED APPLICATIONS

This application claims the benefit of provisional patent applicationSer. No. 62/348,210, filed Jun. 10, 2016, the disclosure of which ishereby incorporated herein by reference in its entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to a semiconductor package and a processfor making the same, and more particularly to a thermally enhancedsemiconductor package, and a process to apply at least one thermaladditive into the semiconductor package for enhanced thermalperformance.

BACKGROUND

With the current popularity of portable communication devices anddeveloped semiconductor fabrication technology, high speed and highperformance transistors are more densely integrated on semiconductordies. Consequently, the amount of heat generated by the semiconductordies increases significantly due to the large number of transistorsintegrated on the semiconductor dies, the large amount of power passingthrough the transistors, and the high operation speed of thetransistors. Accordingly, it is desirable to package the semiconductordies in a configuration for better heat dissipation.

Flip chip assembly technology is widely utilized in semiconductorpackaging due to its preferable solder interconnection between flip chipdies and the laminate, on which the flip chip dies are mounted. The flipchip assembly technology eliminates the space needed for wire bondingand the die surface areas of a package, and essentially reduces theoverall size of the package. In addition, the elimination of the wirebonding and implementation of a shorter electrical path from the flipchip dies to the laminate reduces undesired inductance and capacitance.

Further, semiconductor dies with silicon on insulator (SOI) structuresare trending due to the low cost of silicon materials, a large scalecapacity of wafer production, well-established semiconductor designtools, and well-established semiconductor manufacturing techniques.However, harmonic generations and low resistivity values of the SOIstructures severely limit the SOI's usage in radio-frequency (RF)applications. By using SOI structures in RF fabrications, an interfacebetween the silicon handle layer and an adjacent dielectric layer willgenerate unwanted harmonic and intermodulation products. Such spectrumdegradation causes a number of significant system issues, such asunwanted generation of signals in other RF bands, which the system isattempting to avoid.

To accommodate the increased heat generation of high performance diesand to utilize the advantages of flip chip assembly, it is therefore anobject of the present disclosure to provide an improved semiconductorpackage design with flip chip dies in a configuration for better heatdissipation. In addition, there is also a need to eliminate thedeleterious effects of harmonic generations and intermodulationdistortions.

SUMMARY

The present disclosure relates to a thermally enhanced semiconductorpackage, and a process for making the same. The disclosed thermallyenhanced semiconductor package includes a module substrate, a thinnedflip chip die, a first mold compound component, and a thermally enhancedmold compound component. The thinned flip chip die includes a devicelayer, a number of interconnects extending from a lower surface of thedevice layer and coupled to an upper surface of the module substrate,and a dielectric layer over an upper surface of the device layer. Thefirst mold compound component resides over the upper surface of themodule substrate, surrounds the thinned flip chip die and extends abovean upper surface of the thinned flip chip die to form a cavity over theupper surface of the thinned flip chip die. Herein, the cavity includesa lower region and an upper region that resides over the lower region.The thermally enhanced mold compound component includes a lower portionfilling the lower region of the cavity and residing over the uppersurface of the thinned flip chip die, and an upper portion filling theupper region of the cavity and residing over the lower portion. A firstaverage thermal conductivity of the lower portion is at least 1.2 timesgreater than a second average thermal conductivity of the upper portion.

According to an exemplary process, a precursor package including amodule substrate, a thinned flip chip die attached to an upper surfaceof the module substrate, a cavity over an upper surface of the thinnedflip chip die, and a first mold compound component is provided. Herein,the first mold compound component resides over the upper surface of themodule substrate, surrounds the thinned flip chip die, extends above theupper surface of the thinned flip chip die and surrounds the cavity. Thecavity includes a lower region and an upper region that resides over thelower region. Next, at least one thermal additive is dispersedthroughout the lower region of the cavity and immediately adjacent tothe upper surface of the thinned flip chip die, where the at least onethermal additive includes a number of particulates. A second moldcompound is then applied in the cavity to fill the lower region and theupper region of the cavity such that the second mold compound isdispersed throughout the number of particulates of the at least onethermal additive in the lower region without any air pockets or voids.Finally, the second mold compound is cured to harden the second moldcompound in order to form a thermally enhanced mold compound component,which includes a lower portion with at least one thermal additivefilling the lower region of the cavity, and an upper portion filling theupper region of the cavity and residing over the lower portion. A firstaverage thermal conductivity of the lower portion is at least 1.2 timesgreater than a second average thermal conductivity of the upper portion.

Those skilled in the art will appreciate the scope of the presentdisclosure and realize additional aspects thereof after reading thefollowing detailed description of the preferred embodiments inassociation with the accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The accompanying drawing figures incorporated in and forming a part ofthis specification illustrate several aspects of the disclosure, andtogether with the description serve to explain the principles of thedisclosure.

FIG. 1 shows an exemplary thermally enhanced semiconductor packageaccording to one embodiment of the present disclosure.

FIGS. 2A-2B show an alternative thermally enhanced semiconductor packageaccording to one embodiment of the present disclosure.

FIGS. 3-8 provide exemplary steps that illustrate a process to fabricatethe exemplary thermally enhanced semiconductor package shown in FIG. 1.

It will be understood that for clear illustrations, FIGS. 1-8 may not bedrawn to scale.

DETAILED DESCRIPTION

The embodiments set forth below represent the necessary information toenable those skilled in the art to practice the embodiments andillustrate the best mode of practicing the embodiments. Upon reading thefollowing description in light of the accompanying drawing figures,those skilled in the art will understand the concepts of the disclosureand will recognize applications of these concepts not particularlyaddressed herein. It should be understood that these concepts andapplications fall within the scope of the disclosure and theaccompanying claims.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the present disclosure. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

It will be understood that when an element such as a layer, region, orsubstrate is referred to as being “on” or extending “onto” anotherelement, it can be directly on or extend directly onto the other elementor intervening elements may also be present. In contrast, when anelement is referred to as being “directly on” or extending “directlyonto” another element, there are no intervening elements present.Likewise, it will be understood that when an element such as a layer,region, or substrate is referred to as being “over” or extending “over”another element, it can be directly over or extend directly over theother element or intervening elements may also be present. In contrast,when an element is referred to as being “directly over” or extending“directly over” another element, there are no intervening elementspresent. It will also be understood that when an element is referred toas being “connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present.

Relative terms such as “below” or “above” or “upper” or “lower” or“horizontal” or “vertical” may be used herein to describe a relationshipof one element, layer, or region to another element, layer, or region asillustrated in the Figures. It will be understood that these terms andthose discussed above are intended to encompass different orientationsof the device in addition to the orientation depicted in the Figures.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”“comprising,” “includes,” and/or “including” when used herein specifythe presence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure belongs. It willbe further understood that terms used herein should be interpreted ashaving a meaning that is consistent with their meaning in the context ofthis specification and the relevant art and will not be interpreted inan idealized or overly formal sense unless expressly so defined herein.

The present disclosure relates to a thermally enhanced semiconductorpackage, and a process for making the same. FIG. 1 shows an exemplarythermally enhanced semiconductor package 10 according to one embodimentof the present disclosure. For the purpose of this illustration, theexemplary thermally enhanced semiconductor package 10 includes a modulesubstrate 12, a thinned flip chip die 14, an underfilling layer 16, afirst mold compound component 18, and a thermally enhanced mold compoundcomponent 20. In different applications, the thermally enhancedsemiconductor package 10 may include multiple thinned flip-chip dies.

In detail, the module substrate 12 may be formed from a laminate, awafer level fan out (WLFO) carrier, a lead frame, a ceramic carrier, orthe like. The thinned flip chip die 14 includes a device layer 22, anumber of interconnects 24 extending from a lower surface of the devicelayer 22 and coupled to an upper surface of the module substrate 12, adielectric layer 26 over an upper surface of the device layer 22, andessentially no silicon handle layer (not shown) over the dielectriclayer 26. Herein, essentially no silicon handle layer over thedielectric layer 26 refers to at most 2 μm silicon handle layer over thedielectric layer 26. In some applications, an upper surface of thethinned flip chip die 14 is an upper surface of the dielectric layer 26.For other cases, the upper surface of the thinned flip chip die 14 is anupper surface of the thin silicon handle layer (not shown). The devicelayer 22 with a thickness between 10 nm and 20000 nm may be formed ofsilicon oxide, gallium arsenide, gallium nitride, silicon germanium, orthe like, and the dielectric layer 26 with a thickness between 10 nm and20000 nm may be formed of silicon oxide, silicon nitride, or aluminumnitride. The interconnects 24 with a height between 5 μm and 200 μm maybe copper pillar bumps, solder ball bumps, or the like.

The underfilling layer 16 resides over the upper surface of the modulesubstrate 12, such that the underfilling layer 16 encapsulates theinterconnects 24 and underfills the thinned flip chip die 14 between thelower surface of the device layer 22 and the upper surface of the modulesubstrate 12. The underfilling layer 16 may be formed from conventionalpolymeric compounds, which serve to mitigate the stress effects causedby Coefficient of Thermal Expansion (CTE) mismatch between the thinnedflip chip die 14 and the module substrate 12.

The first mold compound component 18 resides over the underfilling layer16, surrounds the thinned flip chip die 14, and extends above the uppersurface of the thinned flip chip die 14 to form a cavity 28 over theupper surface of the thinned flip chip die 14. Herein, the cavity 28includes a lower region LR and an upper region UR that resides over thelower region LR, and the upper surface of the thinned flip chip die 14is exposed to the lower region LR of the cavity 28. In this embodiment,the lower region LR is at least 1% of the entire cavity 28. The firstmold compound component 18 may be formed from a same or differentmaterial as the underfilling layer 16. When the first mold compound 18and the underfilling layer 16 are formed from a same material, the firstmold compound 18 and the underfilling layer 16 may be formedsimultaneously. One exemplary material used to form the first moldcompound component 18 is an organic epoxy resin system.

The thermally enhanced mold compound component 20 includes a lowerportion with a first average thermal conductivity and an upper portionwith a second average thermal conductivity. The lower portion of thethermally enhanced mold compound component 20 fills the lower region LRof the cavity 28 and resides over the upper surface of the thinned flipchip die 14. The upper portion of the thermally enhanced mold compoundcomponent 20 fills the upper region UR of the cavity 28 and resides overthe lower portion of the thermally enhanced mold compound component 20.In some applications, the upper portion of the thermally enhanced moldcompound component 20 may further reside over the first mold compoundcomponent 18.

The thermally enhanced mold compound component 20 is formed from asecond mold compound component 30 mixed with a thermal additive 32, andhas no air pockets or voids. The second mold compound component 30 maybe formed from a same or different material as the first mold compoundcomponent 18. By definition, materials are different if they includedifferent elements or have a different element composition. In higherperforming embodiments, the second mold compound component 30 may be ahigh thermal conductivity mold compound component.

Compared to the normal mold compound component having a thermalconductivity about 0.8 w/m·k, the high thermal conductivity moldcompound component has a thermal conductivity greater than 2.5 w/m·k,such as Hitachi Chemical Electronic Materials GE-506HT.

In addition, the thermal additive 32 is dispersed throughout the lowerportion of the thermally enhanced mold compound component 20 at a firstaverage density. The thermal additive 32 may have a varied density,which decreases gradually from a bottom to a top of the lower portion ofthe thermally enhanced mold compound component 20. The thermal additive32 may be also dispersed in the upper portion of the thermally enhancedmold compound component 20 at a second average density, which is lessthan the first average density. In some applications, the upper portionof the thermally enhanced mold compound component 20 is void of thethermal additive 32. The thermal additive 32 has a thermal conductivitybetween 10 w/m·k and 5000 w/m·k, which is higher than the second moldcompound component 30. Consequently, the thermally enhanced moldcompound component 20 has greater thermal conductivity than the secondmold compound component 30 alone. Depending on the different densitiesof the thermal additive 32 dispersed in the lower portion and upperportion of the thermal conductivity mold compound component 20, thefirst average thermal conductivity of the lower portion of the thermallyenhanced mold compound component 20 is different from the second averagethermal conductivity of the upper portion of the thermally enhanced moldcompound component 20. In this embodiment, the first average thermalconductivity is at least 1.2 times greater than the second averagethermal conductivity.

Notice that, besides the high thermal conductivity, the thermal additive32 also has high electrical resistivity to accommodate radio-frequency(RF) properties of the thinned flip chip die 14. The thermal additive 32may be formed from a number of micro-level particulates utilizingmaterials such as boron nitride, aluminum nitride, silicon nitride,alumina, beryllium oxide, carbon nanotube, and metamaterials. Boronnitride, due to its extremely high thermal conductivity (between 50 W/mKand 150 W/mK), extremely high electrical resistivity (greater than 1E12Ohm-cm), and low cost, is a desired material for the thermal additive32.

Heat generated by devices in the device layer 22 will travel upward toan area above the dielectric layer 26 and into the lower region LR ofthe cavity 28. The heat then passes downward through the dielectriclayer 26, the device layer 22, and the interconnects 24 to the modulesubstrate 12, which will dissipate the heat. It is therefore highlydesirable to have a high thermal conductivity region immediatelyadjacent to the upper surface of the thinned flip chip die 14 to conductmost of the heat generated by the thinned flip chip die 14.Consequently, the higher the thermal conductivity in the lower region LRof the cavity 28, the better the heat dissipation performance of thethinned flip chip die 14. In this embodiment, the thermal additive 32may directly contact the upper surface of the thinned flip chip die 14in the lower region LR of the cavity 28. If the thinned flip chip die 14does not have the silicon handle layer (not shown), the thermal additive32 directly contacts the dielectric layer 26.

It will be clear to those skilled in the art that more than one thermaladditive may be used to enhance the heat dissipation performance of thethinned flip chip die 14. A thermally enhanced semiconductor package 10Awith a thermally enhanced mold compound component 20A that includes afirst thermal additive 34 and a second thermal additive 36 isillustrated in FIG. 2A. The first thermal additive 34 and the secondthermal additive 36 are each dispersed throughout a lower portion of thethermally enhanced mold compound component 20A. The first thermaladditive 34 and the second thermal additive 36 may be formed fromdifferent materials having different thermal conductivities. Bydefinition, materials are different if they include different elementsor have a different element composition.

Alternatively, the first thermal additive 34 and the second thermaladditive 36 may be dispersed in different portions of a thermallyenhanced mold compound component 20B within a thermally enhancedsemiconductor package 10B as depicted in FIG. 2B. The lower portion ofthe thermally enhanced mold compound 20B includes a first lower portion,which resides over the upper surface of the thinned flip chip die 14,and a second lower portion, which resides over the first lower portion.The first thermal additive 34 is dispersed throughout the first lowerportion, and the second thermal additive 36 is dispersed throughout thesecond lower portion. The first thermal additive 34 and the secondthermal additive 36 may be formed from different materials, and thefirst thermal additive 34 may have higher thermal conductivity than thesecond thermal additive 36.

FIGS. 3-8 provide exemplary steps that illustrate a process to fabricatethe exemplary thermally enhanced semiconductor package 10 shown inFIG. 1. Although the exemplary steps are illustrated in a series, theexemplary steps are not necessarily order dependent. Some steps may bedone in a different order than that presented. Further, processes withinthe scope of this disclosure may include fewer or more steps than thoseillustrated in FIGS. 3-8.

Initially, a semiconductor package 38 is provided as depicted in FIG. 3.For the purpose of this illustration, the semiconductor package 38includes the module substrate 12, a flip chip die 14F, the underfillinglayer 16, and the first mold compound component 18. In differentapplications, the semiconductor package 38 may include multiple flipchip dies. In detail, the flip chip die 14F includes the device layer22, the interconnects 24 extending from a lower surface of the devicelayer 22 and coupled to the upper surface of the module substrate 12,the dielectric layer 26 over the upper surface of the device layer 22,and a silicon handle layer 40 over the dielectric layer 26. As such, thebackside of the silicon handle layer 40 is a top surface of the flipchip die 14F. In addition, the underfilling layer 16 resides over theupper surface of the module substrate 12, such that the underfillinglayer 16 encapsulates the interconnects 24 and underfills the flip chipdie 14F between the lower surface of the device layer 22 and the uppersurface of the module substrate 12. The first mold compound component 18resides over the underfilling layer 16 and encapsulates the flip chipdie 14F. The first mold compound component 18 may be used as an etchantbarrier to protect the flip chip die 14F against etching chemistriessuch as Tetramethylammonium hydroxide (TMAH), potassium hydroxide (KOH),sodium hydroxide (NaOH), and acetylcholine (ACH) in the following steps.

Next, the first mold compound component 18 is thinned down to expose thebackside of the silicon handle layer 40 of the flip chip die 14F, asshown in FIG. 4. The thinning procedure may be done with a mechanicalgrinding process. The following step is to remove substantially theentire silicon handle layer 40 of the flip chip die 14F to create thecavity 28 and provide the thinned flip chip die 14 with the uppersurface exposed to the cavity 28, as shown in FIG. 5. Herein, removingsubstantially the entire silicon handle layer 40 refers to removing atleast 95% of the entire silicon handle layer 40, and perhaps a portionof the dielectric layer 26. As such, in some applications, the thinnedflip chip die 14 may refer to a device including the device layer 22,the interconnects 24 extending from the lower surface of the devicelayer 22 and coupled to the module substrate 12, and the dielectriclayer 26 over the upper surface of the device layer 22, where the uppersurface of the dielectric layer 26 is the upper surface of the thinnedflip chip die 14. For other cases, the thinned flip chip die 14 mayrefer to a device including the device layer 22, the interconnects 24extending from the lower surface of the device layer 22 and coupled tothe module substrate 12, the dielectric layer 26 over the upper surfaceof the device layer 22, and a thin (less than 2 μm) silicon handle layer40 left over the dielectric layer 26, where the upper surface of thethin silicon handle layer 40 is the upper surface of the thinned flipchip die 14. Because the silicon handle layer 40 is removedsubstantially, deleterious harmonic generations and intermodulationdistortions at an interface between the silicon handle layer 40 and thedielectric layer 26 may be eliminated. Removing substantially the entiresilicon handle layer 40 may be provided by an etching process with awet/dry etchant chemistry, which may be TMAH, KOH, ACH, NaOH, or thelike.

Herein, the cavity 28 includes the lower region LR and the upper regionUR that resides over the lower region LR, and the upper surface of thethinned flip chip die 14 is exposed to the lower region LR of the cavity28. The thermal additive 32 is then applied throughout the lower regionLR of the cavity 28 at the first average density as depicted in FIG. 6.The thermal additive 32 may be formed from a number of micro-levelparticulates and may have a varied density through the lower region LRof the cavity 28. In this embodiment, the density of the thermaladditive 32 may decrease gradually from the bottom to the top of thelower region LR of the cavity 28. Applying the thermal additive 32throughout the lower region LR of the cavity 28 may be provided bydispensing the thermal additive 32 immediately over the upper surface ofthe thinned flip chip die 14F and squeegeeing the thermal additive 32into the lower region LR of the cavity 28. Other techniques, such as adirect local dispensing process using an electrostatic header or a localplacement process using Pick-and-Place tools, may also be utilized toapply the thermal additive 32 throughout the lower region LR of thecavity 28. It will be clear to those skilled in the art that more thanone thermal additive may be applied throughout the lower region LR ofthe cavity 28 (not shown).

After the thermal additive 32 is dispersed throughout the lower regionLR of the cavity 28, the second mold compound 30M is applied in thecavity 28 to fill the lower region LR and the upper region UR of thecavity 28 as depicted in FIG. 7. As such, the second mold compound 30Mis dispersed throughout the number of particulates of the thermaladditive 32 in the lower region LR of the cavity 28. Because air pocketsor voids have poor thermal conductivity, formation of any air pockets orvoids will be avoided during filling of the lower region LR and theupper region UR of the cavity 28 by the second mold compound 30M. Thesecond mold compound 30M may further reside over the first mold compoundcomponent 18. A curing process (not shown) is followed to harden thesecond mold compound 30M in order to form the second mold compoundcomponent 30 and complete the thermally enhanced mold compound component20. The curing temperature is between 100° C. and 320° C. depending onwhich material is used as the second mold compound 30M.

The thermally enhanced mold compound component 20 includes the lowerportion filling the lower region LR of the cavity 28 and the upperportion filling the upper region UR of the cavity 28. Herein, thethermal additive 32 is dispersed throughout the lower portion of thethermally enhanced mold compound component 20 without any air pockets orvoids. Since the thermal additive 32 has a higher thermal conductivitythan the second mold compound component 30, the thermally enhanced moldcompound component 20 has greater thermal conductivity than the secondmold compound component 30 alone. Further, if the upper portion of thethermally enhanced mold compound component 20 includes the thermaladditive 32 at a second average density, which is less than the firstaverage density, the first average thermal conductivity of the lowerportion of the thermally enhanced mold compound component 20 is greaterthan the second average thermal conductivity of the upper portion of thethermally enhanced mold compound component 20. In this embodiment, thefirst average thermal conductivity is at least 1.2 w/m·k and the secondaverage thermal conductivity is at least 0.8 w/m·k. The first averagethermal conductivity is at least 1.2 times greater than the secondaverage thermal conductivity.

Finally, an upper surface of the thermally enhanced mold compoundcomponent 20 is planarized to form the thermally enhanced semiconductorpackage 10 as depicted in FIG. 8. A mechanical grinding process may beused for planarization. The upper portion of the thermally enhanced moldcompound component 20 may reside over the first mold compound component18.

Those skilled in the art will recognize improvements and modificationsto the preferred embodiments of the present disclosure. All suchimprovements and modifications are considered within the scope of theconcepts disclosed herein and the claims that follow.

1. An apparatus comprising: a module substrate having an upper surface;a thinned flip chip die comprising: a device layer; a dielectric layerover an upper surface of the device layer; and a plurality ofinterconnects extending from a lower surface of the device layer andcoupled to the upper surface of the module substrate; a first moldcompound component residing over the upper surface of the modulesubstrate, surrounding the thinned flip chip die, and extending above anupper surface of the thinned flip chip die to form a cavity over theupper surface of the thinned flip chip die, wherein the cavity includesa lower region and an upper region that resides over the lower region;and a thermally enhanced mold compound component comprising: a lowerportion with a first average thermal conductivity, wherein the lowerportion fills the lower region of the cavity and resides over the uppersurface of the thinned flip chip die; and an upper portion with a secondaverage thermal conductivity, wherein the upper portion fills the upperregion of the cavity and resides over the lower portion, and the firstaverage thermal conductivity of the lower portion is at least 1.2 timesgreater than the second average thermal conductivity of the upperportion.
 2. The apparatus of claim 1 wherein the thermally enhanced moldcompound component is formed from a second mold compound component mixedwith at least one thermal additive, and has no air pockets or voids,wherein the at least one thermal additive has a higher thermalconductivity than the second mold compound component and is dispersedthroughout the lower portion at a first average density.
 3. Theapparatus of claim 2 wherein the at least one thermal additive isfurther dispersed in the upper portion at a second average density,which is less than the first average density.
 4. The apparatus of claim2 wherein the upper portion is void of the at least one thermaladditive.
 5. The apparatus of claim 2 wherein the at least one thermaladditive is formed from boron nitride particulates.
 6. The apparatus ofclaim 2 wherein the at least one thermal additive is formed from one ofa group consisting of aluminum nitride, silicon nitride, alumina,beryllium oxide, carbon nanotube, and metamaterials.
 7. The apparatus ofclaim 2 wherein the at least one thermal additive comprises a firstthermal additive and a second thermal additive, which are each dispersedthroughout the lower portion.
 8. The apparatus of claim 2 wherein the atleast one thermal additive comprises a first thermal additive and asecond thermal additive, and the lower portion comprises a first lowerportion and a second lower portion, wherein: the first lower portionresides over the upper surface of the thinned flip chip die and thefirst thermal additive is dispersed throughout the first lower portion;and the second lower portion resides over the first lower portion, andthe second thermal additive is dispersed throughout the second lowerportion.
 9. The apparatus of claim 2 wherein the first mold compoundcomponent and the second mold compound component are formed fromdifferent materials.
 10. The apparatus of claim 1 wherein the firstaverage thermal conductivity is at least 1.2 w/m·k.
 11. The apparatus ofclaim 10 wherein the second average thermal conductivity is at least 0.8w/m·k.
 12. The apparatus of claim 1 wherein the first average thermalconductivity is at least 3 w/m·k.
 13. The apparatus of claim 12 whereinthe second average thermal conductivity is at least 2.5 w/m·k.
 14. Theapparatus of claim 1 wherein the lower region is at least 1% of theentire cavity.
 15. The apparatus of claim 1 further comprising anunderfilling layer residing between the first mold compound componentand the upper surface of the module substrate, and underfilling thethinned flip chip die between the lower surface of the device layer andthe upper surface of the module substrate.
 16. The apparatus of claim 15wherein the underfilling layer is formed from a same material as thefirst mold compound component.
 17. The apparatus of claim 1 wherein theupper portion of the thermally enhanced mold compound component furtherresides over the first mold compound component.
 18. The apparatus ofclaim 1 wherein the upper surface of the thinned flip chip die is anupper surface of the dielectric layer.
 19. A method comprising:providing a precursor package including a module substrate, a thinnedflip chip die attached to an upper surface of the module substrate, acavity over the upper surface of the thinned flip chip die, and a firstmold compound component, wherein: the first mold compound componentresides over the upper surface of the module substrate, surrounds thethinned flip chip die, extends above the upper surface of the thinnedflip chip die and surrounds the cavity; and the cavity includes a lowerregion and an upper region that resides over the lower region; applyingat least one thermal additive throughout the lower region of the cavityand immediately adjacent to the upper surface of the thinned flip chipdie, wherein the at least one thermal additive comprises a plurality ofparticulates; applying a second mold compound in the cavity to fill thelower region and the upper region of the cavity such that the secondmold compound is dispersed throughout the plurality of particulates ofthe at least one thermal additive in the lower region; and curing thesecond mold compound to form a thermally enhanced mold compoundcomponent, which includes a lower portion filling the lower region ofthe cavity and an upper portion filling the upper region of the cavity,wherein: the at least one thermal additive is dispersed throughout thelower portion; and a first average thermal conductivity of the lowerportion is at least 1.2 times greater than a second average thermalconductivity of the upper portion.
 20. The method of claim 19 whereinthe second mold compound is dispersed throughout the plurality ofparticulates of the at least one thermal additive in the lower regionwithout any air pockets or voids.
 21. The method of claim 19 whereinproviding the precursor package comprises: providing a semiconductorpackage including the module substrate, a flip chip die attached to theupper surface of the module substrate, and the first mold compoundcomponent over and surrounding the flip chip die; thinning the firstmold compound component down to expose a backside of a silicon handlelayer of the flip chip die; and removing substantially the entiresilicon handle layer to form the cavity and provide the thinned flipchip die with the upper surface, wherein the upper surface of thethinned flip chip die is exposed to the cavity.
 22. The method of claim19 wherein applying the at least one thermal additive throughout thelower region of the cavity is provided by dispensing the at least onethermal additive over the upper surface of the thinned flip chip die andsqueegeeing the at least one thermal additive into the lower region ofthe cavity.
 23. The method of claim 22 wherein applying the second moldcompound to the cavity is provided by compression molding.